Method for forming images

ABSTRACT

When a file having coated thereon an electrically conductive coating which is transparent in a highly oxidized state and nontransparent in a lowly oxidized state or in a reduced state, such as a coating of indium oxide, is heated electrically or by laser beams or oxidized and/or reduced by electrolytic reaction, images consisting of transparent and non-transparent areas are formed on the film. This can be utilized, for example, in a facsimile system.

United States Patent Sobajima et al.

[451 Aug. 26, 1975 METHOD FOR FORMING IMAGES Inventors: Shigenobu Sobajima; Hiroshi Okaniwa; Kiyoshi Chiba, all of Tokyo; Norio Takagi, Ogaki, all of Japan Assignee:

Filed:

Teijin Limited, Osaka, Japan July 11, 1973 Appl. No.: 378,241

Foreign Application Priority Data July 12, 1972 July 17, 1972 Sept. 4, 1972 Dec. 25, 1972 Dec. 27, 1972 May 4, 1973 US. Cl

Int. Cl.

Japan 47-69039 Japan 47-70726 Japan 47-87902 Japan.... 48-368 Japan 48-2232 Japan .1 48-49014 G03G 17/02; HOlS 3/00 Field of Search.... 178/66 A; 346/74 E, 74 ES, 346/74 S, 76 L; 331/945, DIG. 1; 340/174 YC [56] References Cited UNITED STATES PATENTS 3,657,510 4/1972 Rothrock 331/D1G. 1 3,665,483 5/1972 Becker 3,713,996 l/1973 Letter..... 3.740,76l 6/1973 Fechtcr 3,787,210 l/1974 Roberts 346/76 L Primary Examiner-Daryl W. Cook Assistant Examiner--Jay P. Lucas Attorney, Agent, or FirmSherman & Shalloway 11 Claims, 13 Drawing Figures PATENTEDAUBZBISYS 3,902,180

SHEET 2 [IF 8 PATENTEU AUGZBIQYB 3,902,180

SHEET 3 [1F 8 Fig.5

AREA OF PICTURE ELEMENT (mm AMPLlTUDE E (Volt) PATENTEI] M182 6 I975 sum u o a Q l Wl A V PZmSE E wEDPUE m0 mm PULSE WIDTH (psec) PATENTED mnzsms AREA OF PICTURE ELEMENT (mm SHEETS 0F 8 RECORDING ENERGY (mj) 1 I l l l PATENTED AUG 2 6 I975 SHEET 8 BF 8 Emhmim JOEOPZOU DOE 04 PATENTEU mszsms SHEET 7 OF Fig.7!) 0 METHOD FOR FORMING IMAGES This invention relates to a method for direct recording which involves the formation of images on a recording material using electric signals that are generated sequentially with passage of time. More specifically, this invention relates to a method which comprises scanning an original, and converting the resulting picture element signals into images without modulation, or a method which comprises modulating the picture ele ment signals, demodulating the signals, and converting the signals to images. Such a method can be utilized for a variety of applications, for example. as a receiving method for a facsimile system.

A number of methods have been proposed previously for forming images on recording material utilizing elec tric signals generated successively, such as a dry electrosensitive (sparking) recording method. a recording method using laser beams, or an electrolytic recording method The discharge breakdown recording method involves forming an electrically conductive layer of carbon on an insulating material and coating an insulating coating material such as white titanium oxide to form a recording material, applying a voltage of 150 to 200 V between the recording material and a recording needle electrode, and breaking a layer of the titanium oxide by sparking thereby to expose the black carbon layer and effect recording. According to another embodiment, a recording material comprising an insulating base material having formed thereon a thin coating of a metal such as aluminum is used, and a voltage of 50 to 150 V is applied between the recording material and a recording electrode whereby the metal coating is broken by sparking and thus recording is effected (disclosed, for example, in U.S. Pat. No. 2,836,479).

However, these conventional dry electrosensitive recording methods require fairly high voltages for breakdwon by sparking, and also have the defect that dusts and dirts scatter about during recording to give off offensive smell.

A recording method utilizing a laser beam instead of the dry electrosensitive (sparking) recording was proposed (U.S. Pat. No. 3,720,784), which comprises applying a laser beam to a recording material comprising a base and a thin coating of metal formed thereon to evaporate and scatter the metal by the heat energy of the laser beam and thereby to provide micropores in the metal coating, This method also has the defect that during recording, dirts and dusts scatter, and as a re sult, the pores rise in the crater-like form, making it generally difficult to obtain images of high clarity.

An example of the electrolytic recording method is one which comprises flowing electric current from a recording metal electrode to a recording paper impregnated with an electrolytic solution to transfer metallic ions from the electrode and develop colors whereby recording is effected (Horgan Faximile Corporation, Technical Bulletin, July 1967). The known combination of the electrolyte and the metal of the electrode is. for example, a combination of potassium ferricyanide and iron, a combination of phenol and iron, or a combination of dimethyl glyoxime and nickel. Another form of the electrolytic recording method involves forming a layer of a metal such as aluminum on a base such as paper, coating a photoconductive layer composed mainly of zinc oxide, and depositing the metal from the electrolytic solution utilizing the memory effect of the photoconductive layer (see US. Pat. No. 3,010,883).

However, in the conventional electrolytic recording method such as described above, the structure of the recording material is somewhat complicated because of the need for retaining a given electrolytic solution in the inside of the recording material. Furthermore, the recording material is non-transparent in general, and therefore, it is impossible to obtain transmission-type recorded images. Moreover, since the recording material itself contains the electrolytic solution, the recording characteristics are liable to undergo the effect of humidity, and the dimension of the recording material is liable to fluctuate. There is a further defect that the recorded images tend to discolor or bleed out. The base material of the conventional electrolytic recording material generally requires permeability of electrolytic solutions, transparent polymeric films having superior properties in respect of strength, flexibility, dimensional stability, etc., such as a polyethylene terephthalate or cellulose triacetate film, cannot be used as the base material.

The present invention provides a recording method free from the above-described defects and a recording material used in carrying out this method. We have now found that a coating of a low oxide of indium which is substantially non-transparent and has electric conductivity is oxidized by heating with a relatively low energy or by an electrolytic reaction at a relatively low voltage to indium oxide (In O which is substantially transparent and electrically conductive. It has also been found that coatings of low oxide of tin, low oxide of titanium and low oxide of zirconium which is substantially non-transparent, and electrically conductive can be oxidized relatively easily by similar methods to higher oxides which are substantially transparent, and electrically conductive. The work of the inventors also led to the discovery that a coating of indium oxide which is substantially transparent, and electrically conductive is reduced by an electrolytic reaction at a relatively low voltage to a substantially non-transparent indium metal, and that the metallic indium is less susceptible to oxidation than a low oxide ofindium and is stable. It has also been discovered that coatings of SnO- TiO ZrO Cul, CuCl, Ag] and AgCl which are substantially transparent, and electrically conductive are reduced by an electrolytic reaction at a relatively low voltage same as in the case of a coating of ln O to the metals which are non-transparent.

The present invention provides a recording method in which images corresponding to electric signals are formed by using a coating of a metal compound which assumes a nontransparent state and a transparent state as described above.

According to this invention, a method for forming an image on an electrically conductive coating formed on a base material is provided which method comprises successively oxidizing and/or reducing the electrically conductive coating which is substantially transparent in a highly oxidized state and substantially nontransparent in a state reduced to a greater degree than the highly oxidized state, according to an applied electric signal.

The invention further provides a method for forming images from electric signals which comprises successively oxidizing and/or reducing a substantially nontransparent coating of at least one member selected from the group consisting of a low oxide of indium, a low oxide of tin, a low oxide of titanium and a low oxide of zirconium according to electric signals generated sequentially, thereby to form images.

Futhermore, the invention provides a method for forming images from electric signals, which comprises successively reducing a substantially transparent coating of at least one member selected from the group consisting of indium (III) oxide (ln O tin (IV) oxide (SnO titanium (IV) oxide (TiOz). zirconium (IV) oxide (ZrO- copper (I) iodide (CuI), copper (I) chloride (CuCl), silver iodide (Agl) and silver chloride (AgCl) according to electric signals generated sequentially.

An object of this invention is to provide a method for forming images of high resolution power from electric signals which are generated sequentially.

Another object of this invention is to provide a method for forming images composed of a transparent area and a non-transparent area.

Still another object of this invention is to provide a method in which a transmission-type image is obtained by using a transparent base material and a reflectingtype image is obtained by using a non-transparent base material.

Still another object of this invention is to provide a method for forming images at high speed by relatively low energy.

Still another object of this invention is to provide a method for forming stable images which are not affected by humidity.

Still another object of this invention is to provide a method for forming images in which a polyester film can be used as a base material and there is no need for impregnatng the base material with an electrolytic solution.

A further object of this invention is to provide a direct recording method which can be utilized for receiving transmitted images in a facsimile system.

First, the base material and coating that constitute the recording material used in the methods for forming images in accordance with this invention will be described, and then various embodiments of the imageforming methods of this invention will be described.

The base material of the recording material used in this invention may be shaped articles of organic polymers, inorganic materials, and composites of these. Examples of the organic polymers useful in this invention are thermoplastic resins such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyacrylic ester, ABS, polystyrene, polyacetal, polyethylene, polypropylene and cellulose acetate resins, and thermosetting resins such as epoxy, diallyl phthalate, silicon, unsaturated polyester, phenol, and urea resins. These resins can be used either alone or in admixture. Examples of the inorganic material are glass materials such as soda glass, borosilicate glass or silicate glass, porcelains such as those of the alumina, magnesia, zirconia or silica type, metal oxides, and semi-conductors of various compounds.

The base material is in various forms such as films, sheets or blocks. For example, for use in facsimile, flexible films or sheets are preferred, and for use in transmission-type recording materials, transparent or semitransparent films are preferred.

Biaxially oriented polyester films are especially preferred base materials. The polyester films are films of aromatic polyesters, of which polyethylene terephthalate and polyethylene-2,o-naphthalene dicarboxylate are especially preferred. The superiority of polyester films represented by the polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate as base material of the recording material used in this invention is ascribable primarily to their excellent me chanical properties, excellent transparency in the visible region, excellent thermal resistance, and excellent chemical resistance.

The polyethylene terephthalate and polyethylene- 2,G-naphthalenedicarboxylate films have a strength at break of at least 15 Kg/mm at room temperature, and can have a strength at break of more than 40 Kg/mm in the longitudinal direction. These films have a high initial Youngs modulus, usually at least 300 Kg/mm and in special cases, more than 800 Kg/mm' Thus, in conjunction with their low water absorption, these films have extremely good dimensional stability which is important for the recording material used in this invention.

A 50-micron thick polyethylene terephthalate or polyethylene-2,o-naphthalenedicarboxylate film has a transmission of at least 75% with respect to light of a visible region having a wavelength 4,000 A to 7,000 A, and such films are suitable for optical information pro cessing. The polyester films also have fairly high thermal stability. It is also advantageous to perform information processing in the wet state, and in such a case also, the polyester films can be utilized because of their superior chemical resistance.

The biaxially oriented films are those stretched longitudinally and transversely so as to render their mechan ical properties suitable for an intended object. Those which have been stretched 3.0-5.0X in the longitudinal direction, and 2.5-4.5X in the transverse direction are preferred. These films can be produced by a simultaneous biaxially stretching method, a consecutive biaxial stretching method, or a three-stage stretching method in which further longitudinal stretching is performed after biaxial stretching.

The coating of the recording material used in the image-forming method of this invention may be any material which has a first substantially transparent highly oxidized state and a second substantially non-transparent state reduced from the first state both of which states have electrical conductivity and can be converted to each other by oxidation or reduction. The coating preferably has a transmission of visible light of at least 60%, especially at least 75%, in the first highly oxidized state, and a transmission of ,visible light of not more than especially not more than 30%, in the reduced state. Especially those coatings which can be formed at temperatures that do not harm the base of a polymeric material are preferred.

Coatings composed of a low oxide of indium, a low oxide of tin, a low oxide of titanium, a low oxide of zirconium or a mixture thereof have been found to meet the above requirements of the coating and to be convertible to a transparent state oxidized from an opaque state. The low oxide of indium is especially superior in respect of the degree of resolution and stability of the images formed. A coating of a mixture of a low oxide of indium with a small amount (for example, 1 to 20% by weight) of a low oxide of tin is especially preferred because of its enhanced stability.

The low oxide of a metal, as used in the present specification and claims. denotes a metal oxide which is not oxidized to a maximum valency state. The low oxides of these metals are expressed by the following formulae.

For example, a low oxide of indium is a substance which is stoichiometrically expressed by In,O,,(0 v/.\' 1.5). This substance is a black electrically conductive substance obtained by subliming In O in vacuo at a temperature of not less than about 850C, which is considered to be a mixture comprising metallic indium. In O, InO. In- ,O and oxygen.

Coatings composed of indium (III) oxide (In-:0 tin (IV) oxide (SnO titanium (IV) oxide (TiO zirconium (IV) oxide (ZrO- copper (I) iodide (CuI). copper (I) chloride (CuCl). silver (I) iodide (AgI) and silver chloride (AgCl). or mixtures thereof have been found to meet the above requirements of the coating and being able to be converted to a non-transparent state by being reduced from a transparent state. Indium (III) oxide is especially superior in respect of the degree of resolution or stability of the images formed. A coating of a mixture of indium (III) oxide and a small amount (for example. I to 20% by weight) of tin is especially preferred because of its enhanced stability.

The formation of an electrically conductive coating on the surface of the base material can be effected by a method in which a metal oxide which will constitute the coating is coated by vacuum evaporation or sputtering. or a method in which the metal ofa metal compound which will constitute the coating by vacuum evaporation. sputtering. plasma spraying, vapor-phase plating. chemical plating, or electroplating. followed if desired by a chemical treatment such as oxidation. There can also be used a method in which the coating is performed by a thermal decomposition reaction of a metal chloride or the like.

For example. in order to form a non-transparent coating of a low oxide of indium. a vapor of indium oxide is deposited on a base material. In the course of vacuum evaporation. indium oxide loses part of oxygen. and a coating'of a low oxide of indium is formed on the base material.

The formation of a transparent indium (III) oxide coating is effected by heating in air or electrolyzing in an electrolytic solution the coating of indium low oxide formed by the above-described method.

Generally. the thickness of the coating is preferably 50 A to 5.000 A. especially 100 A to 2.000 A. so that the coating exhibits electric conductivity and can be oxidized and/or reduced with a relatively low energy. The surface resistivity is preferably not more than I()() kilo ohms/cm in the case of a coating of indium oxide. Coatings having a surface resistivity of as low as about ohms/cm can be produced at present.

The following methods for forming images by oxidizing and/or reducing the coatings described above have been found.

l. A method wherein a non-transparent coating is successively oxidized according to electric signals to render it transparent, thus forming images.

2. A method wherein a transparent coating is successively reduced according to electric signals to render it non-transparent, thus forming images.

3. A method wherein a coating which is either transparent or non-transparent is successively oxidized and reduced selectively according to electric signals to form images composed ofa transparent area formed by oxidation and an area assuming the metallic lustre formed by reduction.

4. A method wherein a coating which is either transparent or non-transparent is successively reduced according to electric signals to form an area which exhibits the metallic lustre, and then the unreduced area of the coating is oxidized to render it transparent. and thus forming images.

These methods will be described below by reference to the accompanying drawings in which:

FIG. 1 is a view showing the principle of the recording method of this invention by electric current heating;

FIG. 2 is a sketch of a facsimile testing instrument;

FIG. 3 is a graphic representation showing the rela tionship between the amplitude of a recording pulse and the area of a picture element;

FIG. 4 is a graphic representation showing the relationship between the pulse width and the area of a picture element;

FIG. 5 is a graphic representation showing the relationship between a recording energy and the area of a picture element;

FIG. 6 is a view showing a recording device utilizing laser beam;

FIG. 7 is a view illustrating the principle of the recording method of this invention by electrolytic reaction; and

FIG. 8 is a sketch of a facsimile testing instrument equipped with a mechanism for feeding an electrolytic solution supporting material.

I. Method in which a non-transparent coating is successively oxidized according to electric signals to render it transparent, thus forming images.

In this case. the following methods have been found for oxidizing the coating according to the electric signals.

1-0. A method wherein electric current is applied to the coating, and the coating is oxidized by heat generated by the electric current.

1-12. A method wherein the coating is oxidized by applying laser beams thereto and thus heating it.

l-c. A method in which the coating is oxidized by an electrolytic reaction.

In these methods. the transmission of visible light through the coating which becomes a background should be as low as possible in order to obtain images of high contrast. The transmission of visible light is especially preferably not more than 30%. A coating composed mainly of a low oxide of indium is roughly black in color. and is especially preferred for obtaining images of high contrast. In order to lower the transmission. a minor amount of tungsten. molybdenum. tantalum. etc. may be added to the coating material.

The methods lu). 1-12) and 1-0) will be described in greater detail.

l-a. This method involves using a non-transparent electrically conductive coating (for example, a coating of a low oxide of indium) as one electrode and a needle-electrode opposite thereto, applying a pulse voltage which changes in amplitude or pulse width according to information, and oxidizing the coating by Joules heat generated according to the amount of electricity flowing in the coating to render it transparent, thus forming images. Since a solid is evaporated according to the conventional dry electrosensitive recording method. an enormous amount of energy is required, and naturally high voltages and much current are required. However, according to the present invention, the coating can be rendered transparent merely by heat oxidizing it without the need for melting or evaporating a solid, and therefore the invention is very advantageous also from the viewpoint of energy required. Especially, a metal oxide, for example indium oxide, has a very low specific heat as compared with metal (that is, has small heat capacity), and therefore pulse voltage acts effectively for raising the temperature of the area to which the voltage has been applied.

For example, when an energy of 03 watt is applied for 10 second to a coating of a low oxide of indium having a thickness of 1,000 A and an area of 3.14 X cm the temperature of that portion rises to about 400C. assuming that there is no dissipation of heat. Thus, it can be expected that information will be able to be recorded at high speed using low voltage and small current.

FIG. I shows the principle of a recording device for performing this method. The recording material is composed of a base material 1 and an electrically conductive coating 2. The recording device is constructed of a recording needle electrode 3 having a very small area of contact, a return electrode 4 having a relatively wide area of contact, and a pulse generator 6. The reference numeral 5 represents a general wave form of pulse to be applied to the needle electrode 3. When the pulse generator 6 generates a pulse signal, electric current flows from the recording needle electrode 3 to the return electrode 4 through the electroconductive coating. Since the area of contact of the recording needle electrode is small, heat is generated by the electric current at the portion of the coating which is in contact with the recording electrode 3, and that portion is oxidized by the heat. Since the oxidation is effected by Joules heat, the voltage to be applied to the recording potential of the return electrode 4 as a standard.

Using the recording device shown in FIG. 1, the recording characteristics of the coating of indium low oxide were examined. First, pulses of different widths 5 were applied to the needle electrode 3 one by one, and

the changes in the surface of the coating were examined. The results are shown in Example I in Table 1. Furthermore, the recording material in accordance with Example 2 (Table l was fed at a predetermined speed, and pulse signals having adjustable pulse width and amplitude and a certain repeated frequency are applied to the needle electrode 3, whereby the relation between the amplitude and the area of a picture element, the relation between the pulse width and the area of a picture element, and the relation between the recording energy and the area of a picture element were examined. The results are plotted in FIGS. 3, 4 and 5.

tion, and a pulse signal whose amplitude and width change according to information can be used in the present invention.

Furthermore, by using a facsimile testing instrument of the type described in FIG. 2, a pulse-like picture element signal is applied to the needle electrode while scanning the recording electrode and the recording material, and images are formed. The operation of the facsimile tester is as follows: A ribbon-like recording material II is fed from a bobbin 10 through guide rollers 12 and 13, a feed roller 14, a press roller 15, a return electrode 16, a guide roller 17, a feed roller 18 and a press roller 19. Any one of three recording needle electrodes 21 provided on an endless belt 20 driven by a pulley 22 is always in contact with the recording material 11. The recording electrode 21 scans the recording material 11 in the transverse direction according to the movement of the endless belt 20 (this scanning will be referred to as main scanning), and scanns it in the longitudinal direction according to the movement of the feed rollers 14 and 18 (this scanning will be referred to as subsidiary scanning).

Images are formed on a recording material having a coating of indium low oxide using this facsimile testing instrument. The results are given in Example 3 in Table electrode 3 may either be positive or negative with the 1.

Table 1 Example I Example 2 Example 3 Base material ol the recording material -micron thick biaxially oriented polyethylene terephthalate film SU-micron thick hiaxially oriented polyetlrvlene Coating Main composition Method of forming Source substance Needle electrode Material Diameter Needle pressure 5% Black ltltl ohms/em 'l'ungsten 20 microns H) g terephthalate film 3% Black lllll ohms/cm 5"; lilack Silt) ohms/em lungs-ten (Ll mm 2.0 g

Table l Continued Example I 75-micron thick biaxially oriented polyethylene tercphlhalatc film Base material of the recording material Example I 5ll-micron thick biaxially oriented polyctlnlenc terephthalate film Example 3 fill-micron thick biaxially oriented polyethylene terephthalate film Electric signal (pulse) Period l Pulse width (1') Amplitude (E) l scc to ll) ysec 24V Main scanning speed Suhsidiar scanning speed Results l l; A substantially circular. transparent area \\ith a diameter ol It) to I microns \vas l'orined at the electrode-eontacting part ol'the coating according to the pulseuidlh of the signal.

*2: The \ollage. a current and pulse \\idth ol the pulse signal ere measured h a dual beam oscilloscope and the transparent picture element part oi the coating was microscopicall observed. The results are ghen in FIGS. 3 to 5 (solid lines).

"3: An image having a gray scale as formed \\l\ieh had a resolution ol -1/mm and an optical density tlill'erence til at least I.

It is clear from the above description and the results obtained in the above Examples that the method l-a) has the following advantages.

1. Information can be directly converted to images.

2. Since an image can be formed by the chemical change of the coating itself, the recording operation is simple.

3. No development is necessary.

4. The resulting images have good resolution and contrast.

5. By using a transparent material as a base, transmissiontype image can be obtained.

6. High speed recording can be performed using electric signals of relatively low voltage and small current.

7. There is no occurrence of offensive smell or the scattering of dirts and dusts.

to render it transparent and thus form images. The laser that can be used for this purpose may, for example, be YAG laser, argon gas laser or carbon dioxide gas laser. The scanning of the coating by a laser beam is carried out by an apparatus of the type shown in FIG. 6. In FIG. 6, a continuous laser beam generated from a YAG rod is converted to a pulse beam by an acoustic Q switch 32. and further modulated by an optical modulator 33 according to an electric signal 34 containing information. It is then sent to an optical system 35. and reaches a recording member 38 through an iris and a lens. The scanning of the laser beam is performed by a known acoustic optical deflector or rotating mirror (not shown). Using the YAG laser apparatus shown in FIG. 6, an image was formed on a coating ofa low oxide of indium. The results are shown in Example4 (Table 2).

Table 2 Base material of the recording material A SU-inicron thick biaxially oriented polyethylenc-2.o-naphthalenctlicarboxylatc film Coating Composition Method of formation Source substance O; Thickne 600 A Transmission of light at wavelength Sill) A (olor Black Surface rcsistivit) l5() ohms/cm Laser beam Period ('l') l in sec Pulse width (T) (L5 [.LSCC Peak output 4 KW output Ill W Scanning speed 2 cm/sec. Number of bits written 500 hits/cm Result A substantially circular. trans parent area with an average diameter of IS u was formed. The \isilile light transmission of the transparent part was 75 to wow.

8. Since the recording material is of relatively simple structure and stable, it has good storage stability. and the recording characteristics are not affected by external conditions such as humidity. Furthermore. according to this method. recording can be performed in the dry state. and therefore. the recording operation is especially simple. l-b. This method involves applying a laser beam to a non-transparent coating. and oxidizing the coating by the heat generated at that portion thereby of indium that constituted the coating, but by oxidizing Thus, according to method l-IJ), an image is formed by a chemical change of the coating itself without scattering dirts and dusts as in the conventional recording methods utilizing laser beams, and no development is required. This method also possesses the others advantages mentioned in (l-a) above.

l-c. This method involves forming an electrolytic layeronanontransparentelectroconductive coating(for example, a coating of a low oxide of indium) as an anode, disposing a needle electrode as a cathode face to face with the anode through this electrolytic layer, applying to the needle electrode a pulse-like voltage whose amplitude and/or pulse width changes according to information, and thereby anodically oxidizing the coating to convert it to a transparent oxide (for example, indium oxide) and thus to effect the recording of the information.

The principle of a recording appartus for performing this method is shown in FIG. 7. This figure is the same as FIG. 1 except that an electrolytic layer 8 is formed on an electrically conductive coating 2 and a needle electrode 3 is in contact with the electrolytic layer 8. When a negative pulse signal (FIG. 7A) is applied to the needle electrode 3, the electrically conductive coating 2 near the needle electrode 3 acts as an anode and is oxidized.

The electrolytic layer 8 formed on the electrically conductive coating is composed of an electrolytic solution, if desired atransparent or non-transparent support containing an electrolytic solution or polymeric electrolyte. The'electrolytic layer used may be any material that exhibits ion conductivity and has a specific conductivity of at least 10 ohm" cm.

Examples of the electrolytic layer that is used in this method are as follows:

1. Water 2. Aqueous solutions of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, boric acid or phosphoric acid, preferably aqueous solutions of sulfuric acid, nitric acid and boric acid.

3. Aqueous solutions of organic acids such as acetic acid, oxalic acid, tartaric acid. citric acid or succinic acid, preferably aqueous solutions of tartaric acid and citric acid.

4. Aqueous solutions of salts of said inorganic and organic acids, preferably aqueous solutions of ammonium borate, potassium hydrogen sulfate, ammonium sulfate, sodium tartrate, copper sulfate, nickel chloride, and silver nitrate.

5. Alcohols such as methanol, ethanol or glycerol; phenols such as phenol, naphthol, hydroquinone or anthraquinone; ketones such as acetone, methyl ethyl ketone or methyl isobutyl ketone; esters such as ethyl acetate, ethyl propionate or ethyl butyrate; ethers such as dimethyl ether, diethyl ether or methyl ethyl ether; amides such as dimethyl formamide, dimethyl acetamide, pyrrolidone or N-methyl pyrrolidone; nitriles such as acetonitrile, propionitrile or benzonitrile; sulfoxides such as diemthyl sulfoxide, diethyl sulfoxide or diphenyl sulfoxide; and nitro compounds such as nitrobenzene or nitronaphthalene; preferably methanol, butyrolactone, acetonitrile, dimethyl formamide and di methyl sulfoxide solutions.

6. Aqueous solutions of the organic compounds listed in preferably aqueous solutions of methanol, bu-

tyrolactone, acetonitrile, dimethyl formamide and dimethyl sulfoxide.

7. Transparent polymeric electrolytes such as poly(- vinyl benzyl trimethyl ammonium chloride), or other ammonium salts such as poly (sodium acrylate), poly (sodium alginate), or other salts of polyacids.

The electrolytic solutions or polymeric electrolytes may be used in mixture. Above all, solutions containing water or electrolytes, and polymeric electrolytes are especially preferred because voltage required for electrolysis may be low.

The depositing of the electrolytic layer on the surface of the recording material is performed, for example, by a method in which the recording material is immersed in an electrolytic solution, a method in which the recording material is immersed in an electrolytic solution and then withdrawn while retaining the electrolytic layer, a method in which an electrolytic solution or polymeric electrolyte is coated on the recording material, a method in which it is sprayed onto the recording material, or a method in which an electrolytic solution is injected from a needle electrode at the time of recording. Any method can be utilized in this invention by which the electrolytic layer can be retained on the surface of the recording coating.

Preferably, however, a transparent polymeric electrolyte is coated on the recording material, or a support containing a polymeric electrolyte or electrolytic solution is provided on the recording material. A material that forms a porous or hydrophilic film can be used as the support. Examples are a carboxymethyl cellulose film, cellophane film, collodion film, gelatin film, agar film, or polyvinyl alcohol film or paper-like sheet. The thickness of the support is preferably several microns to several hundred microns in order not to affect the low voltage recording characteristics adversely.

Since in this method, it is not necessary to dissolve a specific metallic ion from the needle electrode, the needle electrode can be made of any desired electrically conductive material. Examples of such a material include various metals, alloys, graphite, electrically conductive plastics, glass and ceramics which have been rendered electrically conductive by various methods.

The recording characteristics of a coating composed of a low oxide of indium were examined by a recording apparatus of the type shown in FIG. 7. Example 5 (Table3) refers to the case wherein cellophane film impregnated with water was used as the electrolytic layer 8, and Example 6, to the case where a 20p. thick poly(vinyl benzyl trimethyl ammonium chloride) film coated on the coating was used as the electrolytic layer 8. Furthermore, using the recording material in accordance with Example 6, the relation between the amplitude and the area of a picture element, the relation between the pulse width and the area of a picture element, and the relation between the recording energy and the area of a picture element were examined. The results are shown in FIGS. 3, 4 and 5 in broken lines.

Then, by using a facsimile testing instrument of the type shown in FIG. 8, an image was formed by applying a pulse signal to a recording electrode while scanning the recording material. The facsimile testing instrument shown in FIG. 8 is the same as that shown in FIG. 2 except that it further includes a device 40 for feeding a support 48 (for example, cellophane film) for retaining an electrolytic solution. The operation of the device 13 for feeding the support is as follows: The support 48 is fed from a bobbin 43 through a water tank 44 containing an electrolytic solution 45, a guide roller 46, squeezing rollers 47, 47', guide roller 13, a feed roller change of the coating itself, and any desired electrically conductive materials can be utilized for providing the electrolytic layer and the needle electrode. Further, since water can be used as the electrolytic layer. the opl4, :1 press roller 15, a guide roller 17, a feed roller 49, 5 eration is simple. Furthermore, when a dry polymeric and a press roller 50. In this method, a return electrode electrolyte coated on the coating as the electrolytic 16' in contact with the recording material 11 is used inlayer is utilized, recording can be effected in the dry stead of the return electrode 16 (FIG. 2). Thus, a restate. The method (l-c) also possesses the advantages cording electrode 21 comes into contact with the sur- (l to (7) mentioned above with regard to method face coating of the recording material through the supl l-u).

Table 3 Base material of the recording material Example 5 75pt-thick biaxially oriented polyethylene terephthalate film Example 6 Sim-thick biaxially oriented polyethylene naphthalate lilm Example 7 SUu-thick biaxially oriented polyethylene terephthalate tilm Example 8 5llp-tliick biaxiall oriented pol \eth \'lcne terephthalate lilm Coating Main composition Method of forming Source substance Support Electric signal (pulse) Period ('l'l Pulse width (7) Amplitude (E) Main scanning speed Subsidiar) scanning speed Result Black 10!) ohms/cm" nickel (LUZ mm If) g Water Cellophane l() 1.1. thick) A substantially circular transparent area was formed on the coating immediately below the needle electrode.

ln v/x 1.5) Vacuum evaporation ln. .O. 95"; by weight SnO 56; by weight 400 A Black o ohms/cm platinum (Ll mm Pol \'in \'l hen/.yl trimethyl ammonium chloride) None 3.3 min/min Same as Example 5 Black l()(l ohms/cm nickel 1).] l mm ll) g Water Cellophane [O 1. thick) l() min/min The voltage current and width of the pulse signal were measured b a dual beam oscilloscope, and a transparent picture element Black 50o ohms/cm nickel (LUZ mm all g Water (ion-exchange water) (ellophune ll) p. thick) 500 [.LSCC llll) [.LSCC

l. l m/sec ll mm/sec An image with gray scale having a resolution of 4/inm and an optical difference of l.() as formed on the coating area was observed microscopically. the results are shown in NUS.

3 to 5 (broken lines).

port 48 containing the electrolytic solution. Using this facsimile testing instrument, an image was formed on a coating of a low oxide of indium. The results are shown in Table 3 (Example 7).

When a polymeric electrolyte is used as the electrolytic layer, a support of the electrolytic solution is not required. and therefore, images can be formed by using the facsimile testing instrument shown in Table 2.

As is clear from the above description and the results of the Example. according to method 1-0), the structure of the recording material is simple in structure and has good storability as compared with the conventional electrolytic recording methods, and the recording characteristics of the recording material are not affected by external conditions such as humidity. Furthermore, according to this method. images are formed by chemical 2. Method of forming images by successively reducing a transparent coating according to an electric signal to render in nontransparent.

This method involves forming an electrolytic layer on a transparent electrically conductive coating [for example, a coating of indium (Ill) oxidelas a clthode, disposing a needle electrode as an anode face to face with the cathode through the electrolytic layer, applying to the electrode a pulse signal whose amplitude and/or pulse width changes according to information, and thereby reducing the coating to a nontransparcnt low oxide or metal to record the information.

The principle of the recording device for performing this method is the same as that of the apparatus shown in FIG. 7. A positive pulse signal (FIG. 7B) is applied to the recording electrode 3 for reducing the coating.

The construction of the electrolytic layer 8 provided on the electrically conductive coating 3, the method of depositing the electrolytic layer, and the construction of the needle electrode may be the same as those menstrument of the type shown in HO. 9. The results are shown in Table 4 (Example 13).

As is seen from the above description and the Examples. according to method (2), the structure of the retioned in the description of the electrolytic oxidation 5 cording material is simple as compared with the conmethod of l -c). ventional electrolytic recording methods. and since the Using the recording device shown in FIG. 7, the reelectrically conductive coating itself chemically cording characteristics of two coatings composed of inchanges from the transparent state to the nondium (lll) oxide and a coating composed of copper iotransparent state. the recording operation is simple dide were examined. The results are shown in Table 4 10 as in the method l-c). Furthermore, this method has (Examples 9, 10. ll and 12). An image was formed by the advantage that when a dry polymeric electrolyte applying a pulse signal to aneedle electrode while scancoated on the coating as the electrolytic layer is utining the recording material by a facsimile testing inlized, recording can be performed in the dry state.

Table 4 Base material of recording material Example 9 Stm-thick polyethylene terephthalate film Example ll) Slut-thick polyethylene naph thalatc film Example l l 75p.-thick polyethylene naphthalatc film Example 12 ZOUu-thick polyvinyl chloride sheet Example 13 SOIL-thick polyethylene terephthalate film Coating (non-transparent) Method of formation Source material light at wavelength 5()()() A Surface resistivity Method oi rendering the coating treatment 'l'ransparent (.oating Main composition Thickness Transmission of light at wavelength SUUU A Surface resistivi- Needle electrode (anode) Material Diameter Pressure speed Electrolytic solution or electrolyte Support Results Vacuum evaporation ill- 0;;

450 ohms/cm lo o 4 kiloolnns/cm Platinum (LUZ mm l msec to 4 msec +5 to +|a V Water None Vacuum evaporation 111 0., 95 wtT/( SnO 5 vet/7: 400 A 500 ohms/cm In SnO:

650 ohms/cm Platinum (Ll mm It) msec +30 to +40 V 3.3 mm/min Polytvinyl hen- 1. \l trimcth xl ammonium chlo ride) None Vacuum evaporation lUUU A l I ll) ohms/cm h1 0 (containing a tiny amount of Sn) 501) ohms/cm Platinum 0.02 mm l msec to 4 msec +5 to +16 V Water None Chemical plating (will) A 5 ohms/cm" Cal 7 kiloohms/cm Platinum (1.02 mm Water None 500 ohms/cm" 651) ohms/cm Platinum 002 mm 3 g 500 sec I00 p.sec

1.1 m/sec 2.1 mm/sec Water Cellophane 1 ll) p. thick l: Anodic oxidation method in which a voltage of lot)\' was applied in dimeth \l sull'oxide. *2: Heat-treatment in air at ltltfl'. [or 25 minutes while pl: ing the lilnt under tension.

*3. Heat-treated in air at 220C. for IS minutes hiIe placmg the lilm under tension.

4: lodi/ation method in \\hich the coating as dipped in a I; toluene solution of iodine.

*5: Same as *1: A Sttltslttlttittll) circular black bronn area with high reflectivity was lormcd on the tran *2: Same as l.

"3: Same as H l.

"*4: Same as l.

"5: An image Inning the metalic lustre and high reflectivity as to gra scale.

sparent recording material lmmediatcl below the needle electrode.

rmed on the transparent recording material l'he optical diITerencc is at least HI. 'lhe image had 3. Method for forming images by successively and selectively oxidizing or reducing a non-transparent coating according to an electric signal. and forming the images by a transparent area formed by oxidation and (1-0) above can be utilized.

The voltage of the electric signal is at least 5V, preferably at least V in order to perform sufficient electrolytic oxidation and reduction although depending on Base material of the recording material an area which assumes a substantially metallic color by 5 the thickness ofthe coating, the scanning speed and the reduction. type of the electrolyte used.

This method involves using a non-transparent electri- The pnnclple f a recordmg apparatus for perform cally conductive coating (for example, a coating of a mg thls method the Same that of the appamius low oxide ofindium) as one electrode, disposing a nee Show m pulse 5 7C) whlch dle electrode face to face with the coating through an m Changes to posmve or negatwe generafed electrolytic layer scanning the needle electrode relafrom a pulse genera)? and al)l )lled to a rccordmg tive to the coating. applying between both electrodes at electwde 3 for sekectwely 0Xldlzmg and reducmg a pulse signal which changes to a positive or negative f l' f F l cofmng If thfvoltage of the voltage according to a time sequential information, and recelfed s'gnal hmlted emler a posltlve Voltage (or thus electrolytically oxidizing or reducing the electril5 negatlve voltage) elecmc Signal whl ch changes to cally conductive coating near the needle electrode, a p9smve f negative S'gna] can l obtamed by 'j thereby recording the information on the electrically posmg a sultable d'rect current has voltage on the conductive coating as transparent and non-transparent I areas 7 This method was performed by using theapparatus According to this method, the Characteristics f shown in FIG. 7, and the results are shown in Table 5 cording are hardly affected by the initial transparency (Examples 14 F AS the electrolync layer 8, of the coating, coating of a desired degree of transpar Water was used In Example it and P y yency can beutilized. However, coatings having a visible latel/P01)Vlnylalcohol/potasslum "mate was light transmission of 5 to are especially preferred. 7; used in Example The electrolytic layer utilized for an electrolytic reac- As is seen from the above description and the Examtion may be any material that exhibits ionic conductivples. according to method (3 images of very high conity and the many materials as mentioned with regard to trast can be directly formed on a coating of a desired method l-c) can be utilized. Furthermore. various degree of transparency. Furthermore, since the electrimethods of depositing the electrolytic layer on the surw cally conductive coating itself changes chemically, the face of the recording layer and various supports for the recording operation is as simple as in the case of electrolytic layer as described with regard to method method (l-c').

Table 5 Example l4 Example l5 Example 16* 5tlu-thick polyethylene naphthalate film Coating Main composition Method of forming Source substance Support l-Ilectric signal (pulse) Period ('l'l Pulse width (T) Amplitude (l-I) Main scanning speed Suhsidlar} scanning speed Results ooo ohms/em Nickel (LUZ mm Water None Hlll msec ll) msec (positiw pulse width) +20 in Y I em/sec An image of high contrast as formed hieh consisted of a light-reflecting zu'en liming the color of indium metal and a transparent area.

Heat-treated Zl for 1 minutes under l |a\ial tension.

Low oxide of indium Vacuum evaporation h1 0 9571 by weight Sn();. 5% by weight 400 A 544 Black 500 ohms/cm Platinum (Ll mm lU g lolylsotlium acrylatei/ pol \'\'ln \l alcohol/ potassium nitrate None ion msec ll) msec (positive pulse width) 3.3 cm/scc Same as lixample l-l Black 2 kiloohms/cm Nickel intenal of HLZ mm Water None llll) msee It) msec Same as lixample l4 19 4. Method for forming images by successively reducing a non-transparent coating according to an electric signal to form an area which assumes the metalic lustre, and then oxidizing the unreduced part of the coating to render it transparent.

This method involves using a non-transparent electrically conductive coating (for example, a coating of a low oxide of indium) as a cathode, disposing a needle electrode as an anode face to face with the coating through an electrolytic layer, applying to the needle electrode a pulse signal which changes in amplitude and/or pulse width according to information while scanning the needle electrode relative to the coating, and thus electrolytically reducing the coating to deposit the metal. Then, the entire coating is heat-treated at a relatively low temperature which does not impair the base material (for example, about 120 to 250C. in air in the case of a recording material consisting of a polyester film and a coating of a low oxide of indium) in an oxidizing atmosphere for l to 120 minutes, thereby to oxidize the unreduced part of the coating and render it transparent. Since at such a low temperature, the nontransparent part on which metal has deposited as a result of the reduction of the coating is not oxidized but remains non-transparent, there is formed an image which consists of the transparent area and the nontransparent area.

Since according to this method, the characteristics of recording are scarcely affected by the original transparency of the coating, coatings of any desired transparency can be utilized. However, those having a visible light transmission of to 70% are preferred. The electrolytic solution used for electrolytic reaction may be any materials which exhibit ionic conductivity. The many materials as described with regard to method (l-c) can be utilized. Furthermore, the same methods of depositing the electrolytic solution on the surface of the recording layer and the same constructions of the needle electrode as described with regard to method (l-c') can be utilized.

The voltage of the electric signal is at least 5V, but preferably at least V in order to perform sufficient electrolytic reduction; although depending on the thickness of the coating, the scanning speed and the type of the electrolyte.

The principle of a recording device for performing this method is the same as that of the device shown in FIG. 7. In order to reduce the electrically conductive coating 3 partially, a positive pulse signal (FIG. 7D) is applied to needle electrode 3 from a pulse generator. This method was performed by the apparatus shown in FIG. 7, and the rcsuits obtained are shown in Table 5 (Example l6).

According to this method, images of very high contrast can also be formed on a coating of a desired degree of transparency.

What is claimed is:

l. A method for forming images on an electrically conductive coating formed on a base material which comprises successively oxidizing the electrically conductive coating which is substantially non-transparent in a lower oxidation state and which consists of lower oxides of at least one member selected from the group consisting of ln, Sn, Ti, and Zr, according to an electric signal applied thereto; and rendering said electrically conductive coating transparent to form an image on the base material by selectively oxidizing areas of said conductive coating to higher oxidation states in a predetermined pattern.

2. A method of claim 1 wherein in order to oxidize the coating successively according to the electric signal, the coating is relatively scanned by laser beam modulated according to the electric signal thereby to heat the coating selectively and oxidize it.

3. The method of claim 2 wherein said electric signal is a voltage pulse signal which changes in amplitude and pulse width according to the optical density of an original picture.

4. The method of claim 2 wherein said coating has a visible light transmission of not more than 30% before the oxidation thereof and not less than after the oxidation thereof.

5. The method of claim 2 wherein the voltage pulse signal changes in amplitude according to the optical density of an original picture.

6. The method of claim 2 wherein the voltage pulse signal changes in pulse width according to the optical density of an original picture.

7. A method of claim 1 wherein said coating contains at least by weight ofa low oxide of indium, and has a thickness of 50 to 5,000 A, a surface resistivity of not more than kiloohms/cm and a visible light trans-' mission of not more than 30%.

8. A method of claim 7 wherein said coating contains not more than 20% by weight of a low oxide of tin.

9. The method of claim 7 wherein the coating has a thickness of 100 to 2,000A.

10. A method of claim 1 wherein said base material is composed of a flexible material.

11. A method of claim 10 wherein said flexible material is a transparent biaxially oriented polyester. 

1. A METHOD FOR FORMING IMAGES ON AN ELECTRICALLY CONDUCTIVE COATING FORMED ON A BASE MATERIAL WHICH COMPRISES SUCCESSIVELY OXIDIZING THE ELECTRICALLY CONDUCTIVE COATING WHICH IS SUBSTANTIALLY NON-TRANSPARENT IN A LOWER OXIDATION STATE AND WHICH CONSISTS OF LOWER OXIDES OF AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF IN, SN, TI, AND ZR, ACCRODING TO AN ELECTRIC SIGNAL APPLIED THERETO, AND RENDERING SAID ELECTRICALLY CONDUCTIVE COATING TRANSPARENT TO FORM AN IMAGE ON THE BASE MATERIAL BY SELECTIVELY OXIDIZING AREAS OF SAID CONDUCTIVE COATING TO HIGHER OXIDATION STATES IN A PREDERERMINED PATTERN.
 2. A method of claim 1 wherein in order to oxidize the coating successively according to the electric signal, the coating is relatively scanned by laser beam modulated according to the electric signal thereby to heat the coating selectively and oxidize it.
 3. The method of claim 2 wherein said electric signal is a voltage pulse signal which changes in amplitude and pulse width according to the optical density of an original picture.
 4. The method of claim 2 wherein said coating has a visible light transmission of not more than 30% before the oxidation thereof and not less than 75% after the oxidation thereof.
 5. The method of claim 2 wherein the voltage pulse signal changes in amplitude according to the optical density of an original picture.
 6. The method of claim 2 wherein the voltage pulse signal changes in pulse width accorDing to the optical density of an original picture.
 7. A method of claim 1 wherein said coating contains at least 80% by weight of a low oxide of indium, and has a thickness of 50 to 5,000 A, a surface resistivity of not more than 100 kiloohms/cm2, and a visible light transmission of not more than 30%.
 8. A method of claim 7 wherein said coating contains not more than 20% by weight of a low oxide of tin.
 9. The method of claim 7 wherein the coating has a thickness of 100 to 2,000A.
 10. A method of claim 1 wherein said base material is composed of a flexible material.
 11. A method of claim 10 wherein said flexible material is a transparent biaxially oriented polyester. 